1. Field of the Invention
The present invention relates to an electrical power controller, which is added to a system having a backup generator and transfer switch, to control the backup power of an automatic load while backup power to other loads in the system are controlled by the transfer switch. The electrical power controller also controls the application of power to the automatic load during an exercising of the backup generator.
2. Description of the Related Art
In the related art, devices to control the turn on and off of the backup generator or other backup power source and provide the transfer of the connection of loads from the utility power to the backup power source when a power failure of the utility power occurs have been handled by one device with limited functions. Devices of this type are shown in U.S. Pat. No. 6,172,432 to Schnackenberg et al issued Jan. 9, 2001; U.S. Pat. No. 6,181,028 to Kern et al issued Jan. 30, 2001 and European Patent EP0328706 issued Aug. 8, 1989. Schnackenber et al discloses a load shedding feature for removing and restore different circuits. The other related art devices listed above do not provide other features.
In another related patent, U.S. Pat. No. 4,016,458 to Everhart issued Apr. 5, 1977, shows a device in which essential ones of the distribution amplifiers can be maintained operative by a DC standby power during AC line power hiatus and less important amplifiers are automatically rendered inoperative during power faults to prevent excessive drain on the standby source.
None of the prior art devices above provide control of power source supply to loads when the power utility failure ends.
It would be desirable to have a device to maintain the operation of an automatic load on the backup power source even after the return of normal utility power source and after the automatic load decides to stop, so as to prevent harmful surges or spikes that would occur if the automatic load is switched from a backup source to a utility power source during a required need for the automatic load to be turned on.
It would also be desirable to have a device that can at prescribed times exercise or test the operation of the backup power source only when the automatic load decides that it needs to run.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus an electrical power controller solving the aforementioned problems is desired.
The present invention is an electrical power controller to control the application of power to an automatically controlled load and other loads during and at the end of a power failure in a system.
The electrical power controller can be used in a plant such as a manufacturing plant or sewage treatment plant, which has a backup generator powered by some fossil fuel and a transfer switch as well as normal utility power The transfer switch normally controls the start up of a backup generator upon sensing a utility power failure and transfers the connection of all the loads from the utility power to the backup generator. When utility power returns, the transfer switch normally transfers the connection of all the loads from backup generator power to the utility power and controls the shutdown of the generator. The loads in the system may or may not be automatically controlled loads.
In a manufacturing plant or sewage treatment plant, an automatically controlled load is one like pumps that have sensors and relays to turn them on only when a water level in a well reaches a certain level and turns them off when the water level in the well that it has pumped reaches a lower level. Another example would be a furnace which is controlled to turn on and off by temperature. Such loads benefit from fewer surges and spikes on their power line input, if their sources of supply are not switched while running.
Thus, the instant invention adds a controller, such as programmable logic controller, having inputs and outputs; relays and lamp indicators to the above system.
The controller operates with inputs from the normal utility power source and the automatic load sensors in the automatically controlled load to prevent the connection transfer of automatic loads back to utility power even if the utility power failure has ended and as long as the automatic load sensors still require the automatic load to continue to operate. This is done by disabling the shut down of the backup generator and bypassing the transfer switch to provide the backup generator power directly to the automatic load power input. In the meantime the transfer switch, which has been prevented from shutting down the generator, will transfer other loads back to the utility power at the end of the utility power failure. Once the sensors stop calling for operation of the automatic load will the controller allow the automatic load to run on utility power by reconnecting the automatic load power input back to the transfer switch and release control of the generator back to the transfer switch for shutdown of the generator. At this point the automatic load sensors will have the automatic load turned off, and the automatic load is later ready to use the utility power.
The power controller also uses the same relays and monitors the same inputs to exercise or test the operation of the backup power source at prescribed times when there is no utility power failure and only when the automatic load decides that it needs to run.
Accordingly, it is a principal object of the invention to provide an electrical power controller that keeps an automatic load running on backup generator power even after utility power is restored by controlling the stop and start signal of the generator and controlling bypass relays.
It is another object of the invention to provide an electrical power controller that prevents an automatically controlled load from experiencing damaging power surges or spikes.
It is a further object of the invention to provide an electrical power controller that treats an automatically controlled load differently from other loads in system during and after a power failure of normal utility power.
Still another object of the invention is to provide an electrical power controller, that functions at prescribed times during normal operation of the utility power to exercise or test the operation of the backup power source only when the automatic load decides that it needs to run.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.